Indoor framing projectors are well known for use in theatrical productions. They provide an adjustable focus relatively high intensity beam of light to highlight or create features on stage. Therefore, they have a light bulb or light source, an adjustable focus optical system and may have pattern templates or shutters which can be inserted into the optical system so as to project a certain pattern of light. For example, using a pattern template, a portion of the beam can be shaded so that either the shaded part or the illuminated part looks like a tree or other object, or words. Filters may also be used with these projectors to project different colors of light.
Such projectors have typically been for strictly indoor uses. Electrically, such projectors would be unreliable if subjected to an outdoor environment. However, a framing projector may find many applications outdoors. For example, outlines of specific architectural features such as facias, recesses, entryways, murals or other details could be highlighted. Sharp outlines of the light beam would make interior or exterior features glow uniformly without an apparent source of the beam. Logos or signage could also be projected on a surface, for example the side of a building. Multiple colors or images could be time faded. Changing templates within the projector could announce different events, such as retail sales or concerts.
Moreover, precise control over the cutoff and shape of a light pattern can eliminate light or glare in unwanted areas, thereby reducing light trespass. Rooftops, flags or details around windows could be illuminated without a desirable spill into the windows or into neighboring areas. Entrances, statues or sidewalks could be illuminated without glare on pedestrians or motorists.
Many other applications also exist. For example, sculptures, statues, tables or showroom merchandise could appear to glow by projecting precise outlines of the object from the projector location. Emergency egress directions or other warnings could also be projected. In such applications, illumination could be provided from outside typically inaccessible areas such as hazardous areas, high temperature areas or smoke stacks.
Hundreds of available patterns and colors could create dynamic murals of light. Unattractive buildings or industrial cites such as tank farms could be painted with colored shapes or images. Switching or fading could causes these images to be continually changing or animated. Abstract or realistic scenes could be created to suggested time, place or mood. Artistic images could be easily changed to fit a season or event. Examples include multi-colored geometric patterns, cityscapes, foliage shadows, outdoor scenes such as a desert, seashore, mountain or countryside, sunsets, rainbows, thematic patterns, flags, clouds, stars, window openings, trees and many more.
Moreover, architectural features such as trim, motif or facia designs could be inexpensively or temporarily created by projecting them on otherwise blank surfaces. Designs could be verified prior to construction. Landscapes could be enhanced, such as an effect of moonlight through trees could be projected, or tree images could be projected onto walls. Paths could be sharply defined with glare-free light. Moreover, indefinite mounting locations and obstacles or last minute changes could be easily accommodated with the flexibility of aiming, zoom, focus, shutter and pattern adjustments.
However, prior framing projectors were not suited for such outdoor applications. For one thing, the prior projectors were not weatherproof. Weatherproofing creates a problem not only because the projector must be rainproof, windproof, sunproof, dirt and dust proof, but also because the light source within the projector is high intensity and creates a considerable amount of heat. The light source must therefore be cooled or it will have a very short life. In many prior framing projectors, cooling of the light source was achieved either by convection or with a fan forced flow of air from outside the projector. However, such cooling creates problems with the entry of water, dirt and dust to the interior of the projector in outdoor applications.
Moreover, an outdoor framing projector must have a relatively long throw, or range, through which it must be able to project a visible, focusable image. The optical system required to provide a long range requires a relatively large housing. Since it is for an outdoor application, the housing must be able to withstand buffeting by the elements, without degradation of the performance of the projector. It must also be rugged to withstand a certain amount of abuse to be expected in an outdoor, public, unsupervised application and be economical to produce to be competitive.
The optical system of an outdoor framing projector should also be easily adjustable during daylight hours. In theatrical projectors, the optical system could be adjusted by darkening the room in which the projector was being used. That is not the case outdoors, and the adjustment must be able to be performed easily during normal working hours, during the day. Zoom and focus adjustments must also be easy to perform and rugged to maintain their positions.